While technically it might be possible. I doubt the cruise line would accept it.
If it was inline with the current interpretation of the law, then it would be easy for the cruise lines to sell 1 day shorter cruises with no overnight in each direction, with the passemgers getting their own hotel rooms and get a lot more people interested in the cruise. Yet they do not.
I suspect that even if one disembarks for 24 hours in the same city would not be acceptable to the cruise line. Maybe if one got off in an earlier port ( such as is accepted when one disembarks in Victoria, then reboards in Vancouver). But same port i suspect is a higher hurdle to climb.
Canadian immigration would also have to agree to staff for disembarkation the day before.
Go ahead book the cruise and have your arguement. Let us know how it works out for you.